This will make it just add velocity by 20 up, when you press the spacebar.
EDIT: If you need anymore help, just PM me, I am pretty good at figuring things out.
function bskateboardVehicle::OnTrigger(%this, %obj, %triggerNum, %val)
{
   if(%val)
   {
      if(%triggerNum == 2)
      {
	     %obj.setVelocity(vectorAdd(%obj.getVelocity(),"0 0 20"));
      }
   }
}
I thank you for this. This will stop people from complaining.
But one Problem. Can you get it to delay after it is used? I kept pressing the spacebar button and I flew.